Rollers

So I've had a problem for a while. I cannot find rollers that keep my hair curly all day long. I have tried heated curlers, left them in for hours, take them out to find I have gorgeous curly hair. Half an hour later, my hair is straight again. My hair used to be naturally curly, but due to how much heat I have applied to it over the years, it seems to be pretty much straight when I dry it. 

I am debating buying the 'Scouse Boutique' sleep in rollers, but I have read on other blogs that they aren't comfy and can disturb your sleep. The pictures below are of two different styles I wish lasted all day. As you can see I have very long, thick hair (just past my waist) which I think is the main reason heated rollers just don't work. Also, I spend hours back combing my hair, but because of the weight of my hair it falls flat immediately! The image of the left is my hair with heated rollers and the image on the right is my hair when I have curled it with straighteners. 

If anyone knows any heated or sleep in rollers which will make long thick hair curly for longer than half an hour please comment and let me know! 

xoxox